The present invention relates to a quality monitoring apparatus for a communication channel. Specifically, the present invention is concerned with a channel quality monitoring apparatus capable of providing an improved detection accuracy of a channel error rate in a digital radio transmission system.
In a conventional channel quality monitoring apparatus used in a digital radio transmission system, there has been employed a method of monitoring a frame synchronizing signal or a parity signal etc. generated at a stage of frame synchronization on the basis of a signal received and demodulated in a receiver and demodulator, or a method of generating a preliminary pulse signal including a clock signal or a clock signal added with a predetermined fixed pattern extracted from a signal received and demodulated in a discriminating unit of a demodulator provided in a receiver and demodulator to predict or forecast a channel quality based on the preliminary pulse signal.
However, drawbacks with such conventional channel quality monitoring apparatus are as follows: First is a limited accuracy in channel quality judgement. Second, a large redundant bit length is required for ensuring a high detection accuracy of channel error rate, resulting in a degraded channel utilization efficiency.